Unless you visit and interact with the third-party content provider as a first-party website, their cookies and website data are deleted.

Social media sites often put Share, Like or Comment buttons on other websites. These buttons can be used to track your web browsing — even if you don’t use them. Safari blocks that tracking. If you still want to use the buttons, you’ll be asked for your permission to allow the site to see your activities on the other websites.

Note: Every time you visit a website, it gathers data about your device — such as your system configuration — and uses that data to show you a web page that works well on your device. Some companies use this data to try to uniquely identify your device — known as fingerprinting. To prevent this, whenever you visit a web page, Safari presents a simplified version of your system configuration. Your Mac looks more like everyone else’s Mac, which dramatically reduces the ability of trackers to uniquely identify your device.